The present invention relates to a disposable tap for drawing liquids from a pressurized liquid container, which tap, relative to prior art taps, is modified such that it is attachable preferably in the upper area of the sidewall of the liquid container. The invention further relates to a liquid container unit having an appropriate opening for and provided with said tap.
It has been known for some time to provide in particular small size liquid containers such as beer kegs having a volume of 3 liters, 5 liters, or greater with a disposable tap that can be disposed off together with the container after drawing the liquid contained in the container. Such a tap is mounted in an opening of the sidewall of the liquid container that is located relatively far down the sidewall in order to be able to draw as much liquid as possible. In DE 198 25 929 A1 such a tap comprised of an outer tube inserted seal-tightly into the container as well as an inner tube slidable seal-tightly therein is disclosed. The outer tube has an intake opening that is positioned relatively close to the container wall and can be brought into a congruent position with the intake opening of the inner tube when the latter is pulled outwardly by means of a grip. The inner tube has moreover a discharge opening so that, when the two intake openings are congruent, liquid can flow into the tap and can be drawn from the discharge opening. For closing this tap, the inner tube must be completely pushed into the outer tube again. A disadvantage of this configuration is that, for shutting, the inner tube must be pushed after tapping into the outer tube again and again. When the tube is displaced during pushing, this can lead to unwanted escape of liquid.
On the other hand, the tap disclosed in DE 198 35 569 A1 is very safe and also easy to use. This tap also comprises an outer tube and an inner tube that is slidably arranged within the outer tube. In contrast to the taps that have been known before, the liquid discharge opening is provided in an outer area of the wall of the inner tube that must be pulled out of the outer tube far enough at the beginning of the first tapping operation. A valve that is arranged in the interior of the tube, whose valve cone is forced by the pressure inside the container as well as by the pulling action of an elastic actuating device against its seat, prevents in its closed rest position the liquid from passing and thus prevent the liquid from escaping from the discharge opening. The actuating device for this valve is comprised of an elastic button with a grommet that engages the bead of an extension of a valve plunger that, in turn, ends in the cone of the valve. By pressing down the button, the valve opens and liquid flows through the inner tube to the discharge opening. When the button is released, the valve will close automatically by the restoring force that is caused by the grommet that elastically engages the bead and is assisted by the inner pressure of the container.
According to this proposal, the liquid passes into the tap through openings in the end face of the inner tube. In order to protect the tap from liquid penetrating into it before being first put into operation, this opening is closed off by means of a protective sleeve that is pushed in a seal-tight way across the inner part of the outer tube and is provided at its an end face with a tubular extension having a smaller diameter. The inner tube is provided at its end face with a pin that is sized such that, in the initial state in which the inner tube is inserted completely into the outer tube, it projects into the tubular extension of the protective sleeve and closes it off in a seal-tight way.
Moreover, in the area of the outer tube that is positioned near the container wall a bore is provided for emptying residual liquid, which bore when pulling out farther the inner tube having a corresponding bore, can be brought into a congruent position with the inner tube so that residual liquid can flow into the tap when tilting the container.
A disadvantage of the above described systems is that the tap must be arranged far down the sidewall of the liquid container in order for the container to be emptied to a sufficient degree. Because of the limited space below the tap for drawing liquid, the container must be placed onto a stand or the edge of a table in order to draw liquid into an appropriate vessel, for example, a beer glass. The container therefore can be easily tipped over or it requires a support device specifically designed for it. Moreover, drawing liquid is cumbersome because of the low position of the tap.
It would therefore be desirable to provide a tap that can be arranged at the upper area of a liquid container in order to overcome the aforementioned disadvantages. This tap should also be protected against penetration of liquid before it is put to operation for the first time.
In order to be able to draw liquid from an above-described container or a container unit when the liquid level therein is below the tap, it is necessary to provide or to connect the container a system with which it is ensured that there is always overpressure within the container unit. Such systems are disclosed, for example, in DE 298 22 430.5 or U.S. Pat. Nos. 5,333,763; 4,923,095; or 5,769,282. All of the aforementioned systems are provided with a tap arrangement that is located at the upper end face of the liquid container unit. However, the latter is relatively bulky and large because the tap must project laterally past the edge of the upper end face so that drawing liquid is possible into a vessel arranged underneath. Therefore, there is only the choice of either delivering it separately for assembly at a later point in time or of abandoning the possibility of stacking the container units for the purpose of storage or transport because stacking would not be possible at all or possible only by taking up additional space and static conditions that are not optimal.
There is therefore the need for a system that avoids the afore described disadvantages.
Such a system could be operated by using an inner pressure reservoir or in inner pressure gas cartridge. Such pressure sources are known in principle. For example, DE 298 22 430 discloses a beverage container, for example, a small beer keg, in which a high-pressure bottle is positioned. Of course, it would also be possible to provide a high-pressure source centrally, at the bottom or on the lid of the small keg. The tap proposed for such a system and optionally additional means should therefore not project too far into the center of the container unit in order to allow a variety as large as possible of attachment possibilities for the pressure source.
It is an object of the present invention to provide a tap having the aforementioned desirable characteristic specifications.